Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

En este trabajo se describe e ilustra Commelina rebmanii León-de la Luz, especie nueva propia del ambiente costero del sur de Baja California Sur, México. Se conoce sólo de 2 localidades: la zona de pioneras de dunas de Punta Arena del Sur y la playa al norte de Cabo San Lucas. Una especie cercana parece ser Commelina erecta, de amplia distribución en América, de quien difiere por las menores dimensiones de las brácteas espatáceas y de los pétalos, además presenta el pistilo geniculado con 1 o 2 rizos, y también porque se encuentran en hábitats contrastantes. La especie se encuentra en peligro de extinción debido a la perturbación humana de una amplia zona geográfica, que incluye la de su distribución conocida.

Waltheria glomerata C. Presl. (Malvaceae) se registra por primera vez en Brasil, en el estado de Mato Grosso. Se conocía de México, El Salvador, Nicaragua, Costa Rica, Panamá y Colombia; se amplía su área de distribución para el dominio amazónico brasileño. Este trabajo incluye la descripción de la especie, comentarios taxonómicos, mapa de distribución, ilustración y clave de identificación para las especies presentes en el centro-oeste de Brasil.

El registro sedimentario del lago La Luna, proporciona evidencias sobre la dinámica de la vegetación y el cambio climático durante los últimos 6000 años cal AP (calibrados antes del presente). Se realizaron análisis palinológicos, geoquímicos y material carbonizado para describir los cambios en las comunidades y el ambiente. El registro paleoecológico inició con el establecimiento de elementos del pastizal alpino. El espectro polínico muestra la existencia de bosques de coníferas y de Quercus entre 6000 y 4700 años cal AP, asociados con condiciones climáticas húmedasy baja frecuencia de incendios forestales. Entre 4700 a 2000 años cal AP, hay ambientes más secos, con incremento de incendios forestales y abundancia elevada de Pinus. Durante los últimos 2000 años cal AP, las variaciones en la vegetación muestran un aumento de Abies y una disminución de Pinus asociados con condiciones ambientales relativamente húmedas durante el Clásico (1-650 años dC), el aumento de Pinus en el registro paleoecológico sugiere condiciones climáticas más secas durante el Epiclásico (650-950 dC) y la Anomalía Climática Medieval (950 a 1300 dC). Durante la Pequeña Edad de Hielo (1300-1850 dC) se infieren ambientes fríos con una menor frecuencia de incendios El registro de Zea mays, sugiere actividad humana en el área de estudio desde el año 4680 cal AP.

En este estudio se analiza por primera vez la lluvia de polen en la selva baja caducifolia del cerro El Picante en San José Tilapa (Puebla), ubicado dentro del biodiverso valle de Tehuacán-Cuicatlán. En 3 transectos de 100 m cada uno, se recolectaron bromelias cada 10 m, obteniéndose un total de 32 muestras, de las cuales se recuperaron los palinomorfos y se procesaron por medio de la técnica de acetólisis. Un total de 11,520 polen-esporas pertenecientes a 156 grupos taxonómicos fueron registrados. Los análisis permitieron reconocer taxones regionales, locales y extra locales identificados como señales polínicas. La señal regional estuvo caracterizada por elementos templados, principalmente del bosque mesófilo. La señal local destacó en riqueza e incluyó Asteraceae, Bursera morelensis, B. aptera, Euphorbiaceae, Ceiba aesculifolia y C. parvifolia de la selva baja caducifolia del cerro El Picante; mientras que la señal extra local estuvo representada por Sapindaceae, Caryophyllaceae, Meliaceae y Ephedra spp., que son elementos tanto de selva baja caducifolia como de matorral xerófilo. La comparación de los conjuntos palinológicos con la estructura de la selva baja caducifolia indicaron que Acaciella sp., Asteraceae, Bursera aptera, B. morelensis, Ceiba aesculifolia, C. parvifolia y Mimosa spp. son indicadores polínicos de este tipo de vegetación.

La increíble diversidad específica y ecosistémica sitúan a México entre los países megadiversos del planeta. Los patrones biogeográficos de los taxones del país también muestran una notable complejidad. La parte norte de México se sitúa en la región Neártica, mientras que la parte austral pertenece a la región Neotropical. Entre ambas, principalmente en las sierras Madre y la Faja Volcánica Transmexicana, la mezcla de taxones neárticos y neotropicales determina la Zona de Transición Mexicana. Esta encrucijada biótica hace que la diversidad de México sea tan interesante, no solo en términos de sus especies endémicas, sino también en cuanto a sus variadas relaciones filogenéticas y las hipótesis que se han formulado para explicar cómo taxones de orígenes diversos, se han ensamblado en la Zona de Transición Mexicana. Adicionalmente, el país posee casi todos los tipos de vegetación, con desiertos, bosques tropicales y templados, pastizales y yermos de alta montaña. Se revisa la regionalización biogeográfica del país, reconociéndose2 regiones, 1 zona de transición, 14 provincias y 42 distritos.

Mosquitoes (Diptera: Culicidae) are important vectors of diverse pathogenic organisms, particularly arboviruses and protozoa. The immature stages of mosquitoes occur in a wide range of natural or human-made aquatic habitats. On this basis, some anthropogenic places such as cemeteries, usually serve as thrive and productive artificial-breeding habitats for mosquitoes. Despite being important foci for vector species, urban cemeteries are frequently overlooked in control and surveillance programs. This study evaluates the association of ecological variables and attributes (type of material, presence of flowers, water availability and height from the ground) of the breeding sites with the levels of infestation of mosquito immature stages. In 2017, an entire urban cemetery in Jarabacoa (Dominican Republic) was sampled at two different climatic periods (March: dry and August: rainy) for the characterization of the artificial breeding-sites, collection of immature stages of culicids and subsequent laboratory rearing for species identification. In total 968 containers were studied, containing 7 758 immature stages in 203 (21.0 %) water-filled containers which accounted for four species: Culex quinquefasciatus (50.5 %), Aedes aegypti (47.1 %), Aedes albopictus (1.9 %) and Culex nigripalpus (0.4 %). The mean of A. aegypti immatures in infested containers was roughly two times higher compared to C. quinquefasciatus and significantly lower compared to A. albopictus. The total Container Index (CI) was 20.9 %, and among the type of materials, those made from rock (cement, ceramic, and mud) and plastic had the highest CI = 25.9 % and 23.4 %, respectively. Almost 95 % of the total infested water-filled containers were made of plastic or rock. No association was found between the type of material of the containers and the density of mosquitoes. However, overall, greater densities of immature stages were found at ground than at higher levels. A weak positive correlation between water volume and density was found in some species of immature stages. Significantly higher number of C. quinquefasciatus were recorded in containers with flowers and large water volume. In contrast, A. aegypti immature stages were more frequent in containers without flowers. A weak negative association between water volume and infestations was found for A. albopictus immatures. As reflected of their opportunistic behaviour and broad ecological plasticity, Culex spp. and Aedes spp. mosquitoes were abundant pests in cemetery habitats where were able to breed in almost any kind of water-filled container regardless the type of material. However, our study showed that some ecological variables have critical impact for the development of the immature stages of some species. The health authorities and cemetery keepers can benefit from these results by focusing on the implementation of detailed plans and integrated strategies for the control and prevention of cemetery infestations by mosquitoes.

Spiders have managed to colonize most terrestrial environments, being common in forests. This group has been reported from the ground to the canopy and their vertical distribution patterns have been shown to be variable in different ecosystems. Taking into account this variability, the aim of this work was analyzed the changes in composition and diversity of weaver spiders in a vertical plane in two fragments of dry forest with different structural quality of vegetation. For this purpose, two sites were selected: Reserva Campesina La Montaña (RCM) and Corrales de San Luis (CSL). In each one, four samplings were carried out, two in the dry season and two during the rains. Per fragment, five stations spaced 100 m apart were selected and three points were marked 30 m apart where the plant strata were sampled as: low (20 cm - 2 m), medium (5 m - 8 m) and high (≥ 10 m). To capture the spiders, the foliage beating technique was used. 521 individuals grouped into nine families and 37 morphospecies were captured; RCM being the fragment with the greatest abundance and wealth (n = 335, 28 morphs). On the other hand, the low stratum presented the greatest diversity of the group, regardless of the time and the fragment. A vertical stratification pattern was observed for the community of weaver spiders during the rains period in the RCM, which disappeared in the dry season, whereas in CSL was not possible to observe this pattern in any of the seasons. The results indicate that the spider communities present in BST fragments are able to be vertically stratified, which depends on the time of year and the vegetation conditions in the study area.

General changes in land use have established patterns of modification of native vegetation into agricultural and grazing land. These production systems, as well as social and economic influences, have created diverse landscapes - mosaics composed of varied elements of vegetation cover (forests, crops, pastures, barren fields) that are distributed across spaces in different ways. In this investigation, we determine the distribution patterns of the richness, abundance and diversity of the bird community within the configuration and composition of agroforestry and silvopastoral landscapes. We observed 262 bird species, 6 720 individuals, 23 orders and 54 families within 39 production system mosaics. None of the species accumulation curves in the production systems reached their asymptote, and the calculated estimators predicted a greater number of species than those observed during the survey. In general terms, richness, diversity and equitability indices were highest in the mosaics of agroforestry systems, while abundance and dominance indices were highest in the mosaics associated with silvopastoral and traditional livestock systems. Variables that describe vegetation cover in mosaics have different and independent effects on the diversity of bird assemblages and on the association of land use groups within the mosaics. The positive extreme of the first component contributes to the variance in the model of richness and diversity indices - both the structural components of landscapes and biological components of the assemblages. The area and disposition of different types of elements in the mosaics of the production system landscapes reflect the systematic management of covers, which affects the implications of landscape conservation and restoration practices. Different landscape elements serve as points of contact in the dispersion and distribution of species within these landscapes. The priority of conservation efforts and the first step for the restoration and connectivity of landscapes in the Andean Amazon of Colombia should be the management and protection of covers like old stubble or BFG and BRP. Another approach is the design of landscapes for entire communities of species with respect to certain quantities of habitats in the landscape and the isolation of patches.

Ostracodes are bivalve microcrustaceans with calcium carbonate shells that preserve well in lake sediment. They are very sensitive to environmental variables and are therefore powerful tools in paleoclimate and paleoenvironmental studies that cover time periods from decades to millions of years. Detailed knowledge of species ecological preferences and robust taxonomy are prerequisites for such studies. Such information, however, is still lacking for many areas of the world, including the Neotropics. Previous studies in the northern Neotropics were conducted mainly in the karst lowlands of the Yucatán Peninsula, but higher-altitude areas remained relatively poorly investigated. This study was designed to expand our knowledge of the modern, Neotropical freshwater ostracode fauna, across an altitudinal gradient from the karst lakes in the lowlands of El Petén, Guatemala (~100 - 500 m asl), to the mid-elevation water bodies of the Lacandón forest (~500 - 1000 m asl), to the higher-altitude lakes of Montebello, Chiapas, México (~1000 - 1500 m asl). Eighteen ostracode species were identified in 24 lakes. Ostracodes were absent in Lakes Amarillo and Lacandón (mid-altitude), and San Diego (lowlands). Statistical analysis indicated that the most abundant species, Cypridopsis vidua, Cytheridella ilosvayi, Pseudocandona antillana, and Darwinula stevensoni have a continuous distribution along the entire altitudinal gradient. Other species display more restricted distributions, determined by temperature, precipitation and conductivity. For example, Eucypris sp. is restricted to the lowlands, Vestalenula sp. and Cypria sp. were found only at middle elevations, and a Cyprididae species was restricted to the highlands. Species diversity is slightly greater in warm lakes at middle altitudes (Haverage = 1.09) than in water bodies in the lowlands (Haverage = 0.94) and in cooler lakes in the highlands (Haverage = 0.94). LOESS regressions provided ecological preference information for the four most frequent and widely distributed species, with respect to temperature, conductivity, bicarbonate (HCO3-) concentration, precipitation, and pH. Cypria petenensis, Heterocypris punctata, and Paracythereis opesta display higher abundances in lowland lakes, whereas, Cytheridella ilosvayi, and Pseudocandona antillana prefer lowland and mid-elevation lakes. Environmental conditions in the higher-elevation lakes of Montebello favor the presence of Darwinula stevensoni. Such quantitative ecological information will improve ostracode-based paleoenvironmental reconstructions in southern México and northern Guatemala, and our approach serves as a model for future paleoecological studies that employ other aquatic bioindicators, such as testate amoebae, cladocerans, and chironomids.

Phyllomedusa azurea is a frog species well distributed geographically in South America, including Brazilian biomes as Pantanal and Cerrado. Compared with other anurans from the Phyllomedusinae family, there are few reports on the bioactive potential of skin-derived molecules from this species. In this perspective, the aim of the present study was to evaluate the in vitro antibacterial activity of skin secretion of P. azurea by detection of Minimum Inhibitory Concentration (MIC) of the growth of bacterial indicator strains and to determine if occurs a changing in the bacterial cell envelope permeability. The MIC determination was carried out by the microdilution plate method. The absorbance was measured and analyzed statistically using the t-test to compare two groups (0.05 % of significance). The impact of the crude extract on cell envelope permeability of Staphylococcus aureus ATCC 25923 was conducted by the crystal violet assay, and the absorbance was measured spectrophotometry followed by the calculation of the crystal violet uptake percentage. The specific MIC for S. aureus ATCC 25923 and Escherichia coli ATCC 25922 was 31.25 µg/mL, while for Bacillus subtilis ATCC 6633 was 125 µg/mL and Pseudomonas aeruginosa ATCC 27853 was 250 µg/mL. The treatment with crescent concentrations of frog skin secretion increased the crystal violet uptake by S. aureus ATCC 25923 cells, suggesting an action on the cell plasma membrane. The results demonstrated that the skin secretion of P. azurea presents antibacterial activity and merit further investigations to characterize the bioactive molecules.